Does that make sense? 
Basically, I did a two-part mold. One half did great, the other alligatored on me because it had warmed up to about 90 and I mixed my gelcoat as if it were still 60. Smacks self in head I was laying up my first layer of glass when it started wrinkling on me. I needed to get a part made so I said âScrew it, Iâll just sand and fill the part as necessary.â Well it worked, but it took forever and itâs not exactly as it would be out of the mold. Dang close, but not perfect. Well now I may have a deal for seven more parts. Fixing each one individually is out of the question as far as time goes. Fixing the mold with bondo or bondo/milkshake or something seems like it would work, but itâs not going to be the easiest and again you run the risk of it not being exactly the same as the mold shouldâve been. Is there anyway to put the good half back in the mold and make it stick so that I can just re-do the front of the mold? Thanks in advance!
Take the orginal part and put it back in the good half of the mold. Use whatever means necessary (hot glue) to hold the plug in place. Clay up the flange and build your second half.
Depending on how bad the alligatoring is in the bad half of the mold, it may be easier to repair it. If the shape of the part isnât too complex and if your body working skills are up to par, it shouldnât be too hard. Seven additional parts isnât a very large run and you may be able to scrape by with a simple repair.
we had this problem about a month ago with a wing we were moulding in an enclosed 2 peice mould⌠we were trialing osme semi permanent mould release (that was way way WAY better than we expected⌠5 layers of it we did part 1 of the mould, flipped it up, took off the flanges and went to prep and gel the second part and the plug basically fell out of the mould. i was shocked!! i just stood there looking at the plug shaking my head. Besides the fact that it was a huge waste of materials⌠changes of getting the plug back into the half made mould and alligned perfectly are not so good⌠and seeing as it was an enclosed mould i couldnt take the chance of it having pre-release either.
so from personal experience id say cut your losses and re make the mould and get it right from the start or try and work with what you have and repair it. if its just gatoring and stuff, something i have found really good to do repairs with it mix gelcoat with a powder called Q-Cell to make a bog-ish paste⌠q-cell is fantastic for sanding but just make sure⌠i dont know if its the q-cell or the fact its tooling resin but it tends to go off rather quickly.